32 FOSSIL MAMMALIA OE THE 



from above the level of the molars, apparently with a longer relative interval between it 

 and the angle than in Amb. soricinum, but the outline is not so well preserved. 



The anterior border of the coronoid, so far as preserved, is more vertical and less 

 curved than in AmhJotherimn soricinmn or in Amphitheriiim. The lower margin of the 

 horizontal ramus is continued by a gentle convex line to the end of the symphysis, which 

 is long, narrow, and very little raised from the horizontal level. The breadth of the rising 

 ramus between the fore part of the base of the coronoid and the back part of the condyle 

 almost equals the extent between the fore part of the base of tlie coronoid and the hind 

 end of the symphysis (r). In Ainb. soricinum the same dimension of the rising ramus 

 is equal to three fourths of the extent from the fore part of the base of the coi'onoid to the 

 hind part of the symphysis (fig. \,r). In the present jaw, as in that of Amb. soricinmn, 

 the mylohyoid groove (fig. 2a, g) is represented by a fine linear one, extending from 

 near the entry of the dental canal {d) to the symphysis. The ridge {a) retrogrades from 

 that entry, and augments in depth, or inward inflection, as it approaches the angle [a). 

 The angle which the hue of the ridge {a) forms with the fore margin of the coronoid is 

 more open than in Amb. soricinum. 



The best preserved of the molar teeth {m 3) shows the inner side of the crown divided 

 into two tubercles answering to e and s in fig. 1 b : the anterior one, in like manner, being 

 longer and inclined forward, from a higher level. The main cone rises vertically from the 

 outer side and middle or body of the tooth. The hindmost molar in place seems to answer 

 to m 5 in fig. 1, and, from its relation to the coronoid, should be the antepenultimate molar. 

 There possibly may have been three teeth behind it, if they decreased in size, as in 

 Spalacotherium, but this I think unlikely. An interval for one molar divides the tooth in 

 place {m 5) from the next in advance (?« 3). The molar {m 2) in front of that is obliquely 

 tilted up. The one marked m 1 is obviously smaller : its two roots have slipped from the 

 socket, and the crown is broken off. This would give seven molars, reckoning the last 

 in situ as the antepenultimate one. In advance of the first molar are three premolars, 

 losing size as they advance in position. They are too much mutilated for any conclusion 

 as to the relative length or height of the main cone. Each is implanted by two roots, and 

 the base of the main cone gives indications of fore and hind cusps. The socket of one ante- 

 cedent premolar is definable. Then comes the base of a small canine in its socket, and next, 

 one of a small incisor, in advance of which there is space for two or three sockets of other 

 incisors before the symphysis terminates anteriorly, where the extreme end seems to 

 be wanting. 



The lower border of the horizontal ramus describes a more marked convex curve than 

 in Amb. soricinum. 



The conclusions arrived at fi'om close scrutinising of the indications of teeth in this well- 

 marked form of mandible (fig. 2) are more favorable to generic conformity with the dental 

 formula shown in Amb. soricinum than otherwise. I, therefore, limit myself to regarding 

 the species it represents as being generically allied to the smaller type (fig. 1). 



